Two-dimensional multiwire gas proportional detector for X-ray photon correlation spectroscopy of condensed matter

Details of a two-dimensional (2-D) multiwire gas proportional detector for X-ray photon correlation spectroscopy (XPCS) of condensed matter are described. The characteristics of the gas proportional detector at 8 keV, 0.3 pC anode charge, and 3 bar (absolute) of Xe/10%CO2 are as follows: 8.5×10−7 counts/s (100×100 μm2) dark count rate, ∼μs time resolution, ∼48 and 73 μm position resolution (FWHM) along and across the anode wire direction, respectively, and ∼80% quantum efficiency. The effects of incident photon energy, anode charge (i.e., gain), gas drift depth, and gas pressure on position resolution are discussed. Static and dynamic speckle patterns, measured from disordered aerogel and polystyrene/polybutadiene blends by a partially coherent synchrotron X-ray source, demonstrate that a 2-D multiwire gas proportional detector is very suitable for the dynamic study of condensed matter with relaxation times in the order of μs to 103 s and atomic length scale.